Summary

The web content provides a tutorial on setting up a Wi-Fi Access Point using hostapd and dnsmasq on a Linux system, including configuration of network settings and providing internet access to connected clients.

Abstract

The article is a step-by-step guide on how to establish a Wi-Fi Access Point (AP) on a Linux system using hostapd, a software application that allows users to create wireless networks. It begins with the installation of hostapd and dnsmasq, the latter serving as a DHCP server to assign IP addresses to clients. The tutorial then walks through identifying a suitable wireless interface, configuring dnsmasq.conf and hostapd.conf files to define the network's SSID, IP range, and channel, and starting the AP. Additionally, it covers bridging the AP with an internet-enabled interface to share internet access with connected devices. The article concludes by directing readers to a resource for further learning in reverse engineering and related topics.

Opinions

The author endorses the use of hostapd for creating Wi-Fi networks on Linux systems due to its popularity and open-source nature.
The article suggests that using a wireless adapter with a chipset like Atheros AR9271 is suitable for setting up an AP, implying its compatibility and reliability.
The author emphasizes the importance of dnsmasq for providing DHCP services, indicating its effectiveness in managing IP address allocation for the AP's clients.
The tutorial assumes that the reader has a basic understanding of Linux terminal commands and networking concepts, reflecting an expectation of a certain level of technical proficiency.
By providing a link to Guided Hacking, the author recommends this resource as a valuable tool for those interested in deepening their knowledge in areas such as reverse engineering, malware analysis, and exploit development.

How to Set up an Access Point with Hostapd

In this tutorial, I will show you how to set up a Wi-Fi Access Point using hostapd, a popular open-source software package for creating Wi-Fi networks on Linux systems.

Install Hostapd & Dnsmasq

For the Access Point to work, you’ll need two items:

hostapd — the Access Point software.
dnsmasq — a DHCP server that will provide IP addresses to the clients.

So, start up the Linux system, and in the terminal type:

apt install dnsmasq hostapd

Set up the Access Point

Run the “iwconfig” command to see the available wireless network interfaces (wlan0, wlan1…).

Use a wireless device that supports Access Point Mode. In my case, I am using a wireless adapter with chipset Atheros AR9271 with interface name wlan0.

Once you have identified your wireless interface, set up the configuration files using the nano text editor in the terminal.

nano dnsmasq.conf

And add the following lines.

#Set the wireless interface
interface=wlan0
#Set the IP range for the clients
dhcp-range=192.168.1.2,192.168.1.250,12h
#Set the gateway IP address
dhcp-option=3,192.168.1.1
#Set DNS server address
dhcp-option=6,192.168.1.1

This configuration file will tell dnsmasq to use the wlan0 device and start handing out IP addresses to the clients in the range of 192.168.1.2 through 192.168.1.250. Don’t forget to save the file.

Next, I am going to create another configuration file, this time called hostapd.conf. Open the terminal window and create the file using nano.

 nano hostapd.conf

Add the following lines:

#Set wireless interface
interface=wlan0
#Set network name
ssid=Test-WiFi
#Set channel
channel=11
#Set driver
driver=nl80211

In the example above, an Access Point is defined with the network name “Test-WiFi”, and it will run on channel 11, using wireless network interface wlan0.

Save the file as hostapd.conf.

At this point, you can start the access point using the following commands:

dnsmasq –C /root/dnsmasq.conf
hostapd /root/hostapd.conf

Now hostapd is running, check on another computer or phone to discover a wireless network with the SSID “Test-WiFi”.

Provide Internet Access to the Access Point

Once the AP is running, it’s a common scenario to share an internet connection from another interface. To do that you can use bridge-utils to give internet from a bridge interface by typing the following commands:

brctl addbr br0
brctl addif br0 eth0
ifconfig br0 up

This will create a bridge between br0 and eth0. In my case, eth0 has internet access, so make sure to look for the interface which has internet with ‘ifconfig’ command.

The last step is to modify the hostapd.conf file using nano text editor.

 nano hostapd.conf

And under the wireless interface wlan0 type bridge=br0.

Save the file and restart the AP using:

hostapd /root/hostapd.conf

Now the clients that will connect to the access point will have internet access.

Thank you for reading!

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